The present invention relates to a solution for hemodialysis or peritoneal dialysis.
Dialysis is used as a method of extrarenal purification for combating renal insufficiency: the patient's blood, overloaded with catabolites (or waste materials) is brought into contact with artificial solutions across a membrane.
Such artificial solutions have to have an electrolyte formula resembling that of normal plasma as closely as possible, and contain, for example, sodium, chloride, potassium, calcium and/or magnesium ions. Glucose is often used as an osmotic agent. By way of buffering agents, acetate and lactate ions and especially bicarbonate ions are used, the latter enabling the metabolic acidosis that frequently accompanies renal insufficiency to be combatted.
In point of fact, in the presence of lactic or acetic acid and at a pH of approximately 5.5, bicarbonate ions form complexes of the Ca(HCO.sub.3).sub.2 or Mg(HCO.sub.3).sub.2 form with calcium or magnesium ions.
These complexes are initially soluble, but their accumulation brings about a continual loss of carbon dioxide (CO.sub.2) which leads to an increase in the pH.
As soon as the pH is greater than or equal to approximately 7.5, the calcium and magnesium complexes are converted and precipitate in the form of virtually insoluble carbonates (CaCO.sub.3 or MgCO.sub.3).
To avoid these precipitations, an attempt has been made to abolish all bicarbonate ions and to retain only agents generating the said bicarbonates in vivo, such as acetate or lactate ions.
The conversion of these ions to bicarbonates is not, however, complete; in addition, there is a resultant accumulation of acetates or lactates, which contributes to an increase in the patient's acidosis, the onset of metabolic disorders and hemodynamic disorders.
Other methods have been envisaged for avoiding the formulation of insoluble carbonates:
the continuous bubbling of CO.sub.2 into the dialysis solution, to maintain the pH below 7.5 and thereby avoid the formation and precipitation of calcium or magnesium carbonates;
the preparation of solutions for dialysis free from calcium and magnesium ions, and the separate and simultaneous intravenous administration of these ions;
the preparation of separate solutions, one of them, alkaline, containing the bicarbonates and the other, acidic, containing the calcium and magnesium, these two solutions being mixed at the time of dialysis;
the addition of calcium- and magnesium-complexing agents, capable of preventing their precipitation.
Not only are all these methods tedious, complicated and risky, but they also require the use of specific and costly equipment; in addition, none of these methods leads to the certain abolition of the carbonate precipitates in the apparatus of the artificial kidney or in the peritoneal cavity; finally, the application of such methods is especially thwart with problems in the case of ambulatory continuous peritoneal dialysis, which necessitates approximately 4 exchanges per 24 hours, sterile dialysates and strictly aseptic conditions.